Gauging device and method



L. F. POLK I GAUGING DEVICE AND METHOD Aug. 15, 1944.

Filed Oct. 26, 1942 2 Sheets-Sheet'l INVENTOR. .A'M; J AM 1944- L. F. POLK 2,356,003

I GAUGING DEVICE AND METHOD Filed 001:. 26. 1942 2 Sheets-Sheet 2 INVENTOR.

Patented Aug. 15, 1944 UNITED GAUGING DEVICE AND METHOD Louis F. Polk, Dayton, Ohio, assignor to The Sheflield Corporation, Dayton, Ohio, a corporation of Ohio Application October 26, 1942, Serial No. 463,415

' 10 Claims. (01. 33-199) This invention relates to the making-or testing of internal threads.

One object of the invention resides; in the method of making and testing an internal thread of a threaded part whereby the same thread form that is produced on the threaded part is also pro-- duced, at the same time or in the course of the same operation, on a strip of suitable material which can then be used as a basis of comparison to check the thread form, pitch or other thread characteristics.

Another object of the invention resides in the method whereby an internal thread can be simul-'- taneously made on a thread ring gauge or the like and a rigid blade which has been applied in a substantially radial position to the ring gauge in fixed association therewith but adapted forremoval after the thread is ground or otherwise formed on both of these members. 1

Another object is the provision of an internally threaded ring gauge or the like having a separate strip of rigid material connected thereto and provided with an edge portion which is cut in exact correspondence to the thread in the ring and adapted to be released from its association with the ring so that it may be used to show the thread form, pitch or other characteristics of the internal thread of the ring.

Other objects and advantages of the invention will be apparent from the following description, the appended claims and the accompanying drawings in which:

Fig. 1 is a central transverse section through a thread ring gauge and an associated strip on which the thread form of the gauge is to be produced in accordance with the method of the present invention;

Fig. 2 is an exploded view of the stripan'd its fastening means;

Fig. 3 is a front elevation of a face plate of a threading machine, showing how the gauge is supported; I

Fig. 4 is a transverse section on the line 4-4 of Fig. 3; V V

Fig. 5 is a view, partlyin section, showing a ring gauge and its associated strip;

Fig. 6 is a view of the formed strip; and 1 Fig. 7 is a transverse section through-a face plate and the parts carried thereby and illustrating a modified form of the invention.

Referring more particularly to the drawings by reference numerals, I0 designates an internally threaded ring, such as a thread ring gauge for comparing or gauging the external'threads of workpieces. The thread ring comprises a body portion having a pair of substantially radially extendin slots H extending inwardly to the threaded portion and extending outwardly to circular holes l3. Ordinarily there are a plurality of these slots II and, in addition, another slot which extends clear through the body portion and which provides for expansion or contraction for initial setting or to take up wear. Adjacent parts of the body portion are secured together by means of a threaded attachment 15. The threads I6 on the body portion maybe formed by a milling or turning operation and then ground. After the threads are ground they may be subjected to a suitable lappingoperation.

There is difliculty in obtaining such access to the internal threads of a threaded part as permits accurate measurement or comparison of the thread size, pitch, angle, etc. In measuring or comparing external threads they may be read ily subjected to an optical comparator, and any deviation from a desired configuration can be readily seen, but that is not the case in con nection with intemal threads. Heretoio-re cast strips of a suitable hardening material have been used to make an impression or casting fror'ninternal threads 'to be inspected or gauged and then this casting or impression hasbeen used as a basis of comparison or test. Due to the dimculty and time involved in this proceeding, how ever, and due further to the possibility of shrink age and deformation in the process of making mined relation with respect to the thread ring before the thread form is finished on the ring,

and an edge of the strip is then serrated in exact accordance with the thread serrations and by the same instrumentality that producesthe thread on the thread ring. While, for-exemplary purposes, only one of the "several slots of the thread ring are shown as provided with a strip of rigid material of the character mentioned, it will be obvious thatthe invention is not to be limited to the precise arrangement as herein shown and described. V} j 'In accordance with the forrn of construction shown in Figs. 1 to 6 inclusive, a strip l! of a suitable fastening which, as herein shown, em-

bodies a bolt l8 extending through one of the" holes I 3, the bolt having a slot IS in which the outer portion of the strip I! is received. The strip I7 is preferably provided with inclined shoulders engaged by Washers 2| which have conical surfaces 22 engaging the shoulders 20 with a wedging action to hold the. strip l'l firmly in place. A wing nut 23 threaded on the end of the bolt holds these parts firmly in position in a readily detachable manner. The clearance between the cylindrical surface of the bolt and the hole I3, and the clearance between the sides 7 of the strip I! and the sides of the slot II in the ring are small enough so that there is no substantial freedom of motion of these parts. The ring Ill, either before the threads. I'B are enters the thread ring the strip 33 can be removed and inspected as by an optical comparator or by other suitable inspecting or testing milled or after milling and before they are ground to final form, is secured by means of suitable V holding clamps 25 on a face plate 26 of a thread ing machine, such as a thread grinder As will be readily understood, the face plate is rotated in timed relation to the axial movements of the grinding wheel 21 so that the threads will be accurately ground. At the same time the grinding operation is performed on the ring, and by means of the same instrumentalities, the inner edge portion of the strip I! which initially projected inwardly beyond the thread to be produced, will be ground to serrated form, and the form of the serrations Will exactly correspond to the thread form in the ring in all respects. The strip lTcan then be removed and used as a basis of comparison or 'measurement of the exactly similar threads of the ring itself. The thread form may be seen, for example, by using the strip [1 on an optical comparator to determine if the pitch, included angle, thread size, etc., conform to some predetermined standard.

If the thread of the ring is to be lapped after the grinding operation takesplace, the strip I! may remain in place until after the lapping operation is completed, so that the strip 11 will show exactlyv What thread form is present in the rather inaccessible internal threads of the ring.

As shown in Fig. 1, one end of the strip [1 may project out axially a substantial distance outside of the thread ring, and the axial travel of the grinding wheel may be stopped after'passing along and-cutting this projecting portion of the strip and before a cut is actually made on the partially formed or milled threads in the ring itself. This projecting portion of the strip may be inspected either in place in the ring or after removing it temporarily from the ring to ascertain if the thread form is correct. If the thread form is proper, then-the threading operatio'nmay be carried on, simultaneously grinding the thread ring and the strip to the same conformation. This produces the finished strip Ila as shown in Fig. 6.

In the form of construction shown in Fig. '7, the thread ring I0 is mounted on the face plate 26' in the same manner as previously described. This ring l0 may incorporate a strip I! if --desired, although in this form of construction the strip may be omitted entirely from the ring l0 itself. Arranged outwardly of the -ring gauge I0 is a ring or plate 28 supported-bysuitable clamping bolts 29 on the faceplate 26'. The ring 28 has a cylindrical hole 3!] which is somewhat larger in diameter than the maximum diameter' of the threads to be produced on the ring Ill. The ring 28 is'also provided with a hole 3| and a radial slot 32 similar to the hole Band slot ll in the ring gauge 10 shown 71 means to determine if the thread shape and sizeare correct. If the are correct, the setting of the wheel 21 is maintained and the machine is started again Without even requiring the replacement of the blade 33, and the internal-threads are then cut on the ring exactly the same as they had previously been cut on the strip 33. If an additional stn'p I1 is used in a slot of the ring I0 itself, this strip [1 may be again inspected after the threads are finished, and may be retained to form a basis of comparison by the manufacturer in case ring replacement or regrinding should subsequently be ordered.

By measuring accurately the distance from the serrated end of the strip to the straight outer edge, and having determined the distance from the slotted portion of the bolt IE to the center of the ring gauge, the diameter of the thread in the thread ring may also be computed directly from the finished strip I! itself.

While the article herein described and the method herein referred to constitute preferred embodiments of the invention, it is to be understood that they are not limited to the precise examples employed for purposes of illustration, and changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What isclaimed is:

1. In the method of testing an internal thread of a threaded part, the steps comprising cutting the thread on the part and cutting serrations corresponding to the thread form on a separate strip of material temporarily held in fixed association with the threaded part, by means of the same threading tool and with the same machine setup.

2. The method of testing an internal thread of a threaded part, comprising cutting the'thread on the part while concomitantly with the same cutting 'tool cutting serrations of corresponding form on a separate strip of material held in a recess in the part.

3. The method of making a separate test strip having external serrations corresponding in form and size to the threads of an internally threaded ring, comprising grinding the serrations on the strip and the threads in the ring with the same grinding tool and the same machine setup and while the strip is secured in a recess in the ring.

4. The method of making a test strip showing the exact reproduction on an external surface thereof of an internal thread of a ring gauge, comprising grinding serrations on the strip while the strip is temporarily but rigidly held in a recess in the ring gauge during the time the thread is being ground and employing the same grinding instrumentality in such operation.

5. The method oftesting an internally threaded ring having a radial recess comprising-releasably securing a separate rigid strip of material in the recess in the ring so the strip projects inwardly beyond the finished thread form, and simultaneously grinding the thread on the ring and thread form serrations on the strip.

6. In combination, an internally threaded rin having a substantially radial slot extending to the thread opening, a separate strip of rigid material having a serrated edge portion cut in exact correspondence to the thread in the ring and reproducing any errors in the ring thread form, and means extending through the ring parallel to the ring axis and rigidly securing the strip in said slot.

'7. In combination with an internally threaded ring gauge having a slot extending inwardly to the thread opening, a separate strip of rigid material substantially filling said slot, and wedge means engaging the outer portions of the strip and securing the strip rigidly to the ring gauge whereby thread serrations can be made on both the strip and the ring gauge by the same instrumentality at the same time.

8. A thin fiat metal blade having means at one portion thereof for detachably securing the same in a predetermined position to a thread ring gauge so as to project to the thread opening, and having at an opposite portion thereof a ground serrated surface the serrations of which correspond exactly in form, pitch and size to the sectional form of the thread of the ring gauge and thus reproduce any error in the thread form of the ring gauge.

9. A thin fiat metal blade adapted for insertion in a radial slot of a thread ring whereby the blade and the ring can be threaded by the same instrumentality at the same time, said blade having opposite side portions of wedge form and providing means for securing the blade in the ring.

10. In combination, a separate strip of rigid material having means at one portion thereof for detachably securing the same in a predetermined position in a slot of a ring gauge to project inwardly to the thread opening, and a securing bolt adapted to pass through the ring gauge and having means for securing the blade and the ring gauge in rigid association with one another.

LOUIS F. POLK. 

